Slowing down the pumps?

[ajfedorec]

Hi,

I’ve been using the reactors as chemostats rather than turbidostats but the lowest pump rates I’ve tried (they seem to plateau below 0.001 ish) produce a dilution rate which is still too high for my purposes. Is it possible to slow the pumps down or is it only possible to change the frequency at which they pump.

Thanks in advance.

[harrison]

Hey! You can indeed reduce the voltage which is routed to them in the software. In the PumpModulation function they are generally set completely ON for a short time. For example:
setPWM(M,’Pumps’,sysItems[item][‘In1’],1.0*float(sysData[M][item][‘ON’]),0)
There is a “1.0*” element in there, which is saying to set the PWM voltage to its full value. You could reduce this somewhat to slow them down, though if you make it too low they won’t have sufficient power to overcome inertia and get spinning.

A more reliable/effective method might be to instead change the period of the PumpModulation function. Currently the pumps activate for a short time each minute; if you changed this to 10 minutes you could get lower dilution rates.

[Vincent K]

Hi everyone,

we’re having the exact same problem right now.
Has anyone tried out the solution given above yet and can confirm whether it works or not?
We’re also open and thankful for suggestions and solutions on how issues along the way were fixed.

Thanks a lot in advance.

[Author]

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